Wing Mirror Glass Not Heating

[dan4291]

Hi All

 

Ages since I posted anything on here! Still have a Fabia Monte Carlo estate in our household but I now drive a Renault Megane RS Cup so leave the dependable Monte as our family wagon driven by my other half mostly. Unfortunately I've found something broken on it, and that's the driver's side heated wing mirror glass. It doesn't heat up at all, which as you can imagine is posing a problem on cold morning (first world problem I know, but still annoying!). Any ideas what could be causing it? Would it be a fuse, the mirror glass itself or something more complicated? Just wondering where to start really.

 

Thanks

[delta925]

A broken wire is a possibility.

Since on the door the power most likely comes through the connector and group of wires that pass through the boot between the main body and the door.

Look up the numerous posts about door locking and window problems e.g.

 

https://www.briskoda.net/forums/topic/403575-electric-window-woes-onetouch-fob-and-key-2011-facelift-16cr-tdi/

 

https://www.briskoda.net/forums/topic/417487-few-little-problems/?tab=comments#comment-4757298

 

https://www.briskoda.net/forums/topic/407237-fabia-ii-2010-drivers-door-lock-mechanism-problem/

 

https://www.briskoda.net/forums/topic/425163-broken-wire-rubber-door-connector-again/?tab=comments#comment-4823337

 

 

[SuperbTWM]

You should start by taking the glass off and see if you have power to the terminals and check the heater for continuity

[spartacus68]

Before you start removing mirror glass and tracing wiring, check obvious things like fuses. Incidentally, check that the mirrors are actually set to heat on the switch. If the switch is set to adjustment as in left and right it won't heat. The switch needs to rotate round to the heated element icon.

[Breezy_Pete]

8 hours ago, SuperbTWM said:

You should start by taking the glass off and see if you have power to the terminals and check the heater for continuity

 

I tried this on a mk1 and eventually...learned that it only goes live with engine running; ignition on wasn't sufficient. Might save you some frustration...

 

I would suggest that mk2's seem to have particularly fragile door wiring from what I see on here so I'd eyeball that carefully before anything else: as delta says.

 

[Sittingbull]

On ours we noticed we were unable to move the electric mirrors before we noticed that only one mirror actually heats. At this point we have changed the switch (£30 from TPS) to no avail, fuses are good as well. Once we changed the switch and the electric adjustment was still not working we kind of worked out it's most likely the wiring going from the drivers door through the pillar into the mirror.

 

We hadnt had any need to worry about the heated element until recently, and that's when we noticed that only the passenger side mirror heats up.

 

So we're guessing it's a wiring loom problem. And a pain.

[mrgf]

Broken wires in the door bellow are the most LIKELY suspect! Common fault on these for mirrors and/or windows.

[KenONeill]

It's also not unknown for the heater elements to burn out, particularly on models where isolating the adjuster motors (centre position on the joystick) makes the mirror heaters permanently live rather than "live when the HRW is on".

[mrgf]

On 27/11/2018 at 14:23, KenONeill said:

It's also not unknown for the heater elements to burn out, particularly on models where isolating the adjuster motors (centre position on the joystick) makes the mirror heaters permanently live rather than "live when the HRW is on".

 

 

Dunno about that-My mirror heaters come on with the switch set to heat, not with heated rear window.

[KenONeill]

On 27/11/2018 at 14:23, KenONeill said:

It's also not unknown for the heater elements to burn out, particularly on models where isolating the adjuster motors (centre position on the joystick) makes the mirror heaters permanently live rather than "live when the HRW is on".

 

34 minutes ago, mrgf said:

 

 

Dunno about that-My mirror heaters come on with the switch set to heat, not with heated rear window.

All you've done there is reword what I said.

[rum4mo]

1 hour ago, KenONeill said:

 

All you've done there is reword what I said.

 

I'm sure that you are aware that on some cars, the mirror heater either comes on with the timed rear window heater, or can only be enabled with the rear window heater on.

 

On these cars, if they are the same as similar VW Polos, you can switch on the mirror heaters and they will be on all the time the engine is running rear window heater on of off!

 

I came from cars that had this function wired sensibly, then bought a new Passat 4Motion and by the time I started reading stories on motoring forums about burning out heaters if you left them on too long, I had trashed my Passat's mirror heater tapes!  I think that that 2000 B5 Passat even came without a timer of the rear window heater.

[SuperbTWM]

8 hours ago, rum4mo said:

I came from cars that had this function wired sensibly, then bought a new Passat 4Motion and by the time I started reading stories on motoring forums about burning out heaters if you left them on too long, I had trashed my Passat's mirror heater tapes!  I think that that 2000 B5 Passat even came without a timer of the rear window heater.

 

Just to throw a little curve ball into the mix, The mk1 Audi TT had heated wing mirrors all the time, whether it was -10C or 30C, no way to turn them off, mine both still worked at 7 years old and 65,000 miles.

 

you must get what you pay for 

 

 

 

 

[rum4mo]

True though in the case you mentioned the VW Passat 4Motion would cost more new than the MK Audi TT, thing is some VW Group marques pick a clever set of "standard additions" to fit to certain models, in this case, Audi would have included thermostats into the mirror assemblies on all their models, maybe even from the bottom of the range - VW, SEAT and Skoda never ever did that and so this issue can occur.

 

Edit:- this was one thing that came out of the discussion on mirror heater failures in the Passat forum, equivalent A4 B5s did have thermostats to protect the mirror heater tapes and so Audi A4 B5 folk were replying that it was not possible for this to happen, must be some other problem causing it - wrong!

Edited 30 November, 2018 by rum4mo

[Breezy_Pete]

I faintly remember seeing options in VCDS for how the mirror heating works, but I may be thinking of something else.

Anyone know if you can adjust functionality so that it does just come on for a set time from start-up, or only on with HRW?

I can look myself at some point, but don't have the laptop with me today.

[rum4mo]

The trouble might be, in be able to set it to come on for a set period, ideally you would need to a "push button" momentary ON/OFF button to set logic, as it stands, all these cars I've seen have a switch - and that would stay in the ON position after it had timed out.

 

Obviously you can't satisfy everyone's needs, but a momentary ON and OFF button active at all times the engine is running, with a short timer, would suit all my needs.

 

Currently with varying low temperatures, I often reverse out of the garage, close the garage door, get back into the car and all the windows and mirrors have misted up, switch on mirror heaters, by the time I have reached the top of the driveway mirrors cleared so mirror heater switched off and forgotten about until the next time. Misted windows cleared by moving windows down/up, front/rear screens cleared by a single wipe of the wipers.

[Breezy_Pete]

6 hours ago, rum4mo said:

The trouble might be, in be able to set it to come on for a set period, ideally you would need to a "push button" momentary ON/OFF button to set logic, as it stands, all these cars I've seen have a switch - and that would stay in the ON position after it had timed out.

 

Not sure why it matters that the switch would still be in the 'heating' position, if the heating had timed out?

 

Anyway, I was right, on my Polo 9N you can alter the times that the mirror heating and HRW function for before automatically switching off; adaptations within module 09 central electrics:

 

 

 

Did a little tweaking myself while I was in there, wasn't keen on either of the standard settings.

Edited 30 November, 2018 by Wino